System of speed governing



Nov. 25, 1930. H, B, TAYLOR 1,783,162

SYSTEM OF SPEED GOVERNING I Original Filed May 16, 1919 4 Sheets-Sheet l 5/ M T M2 9" Z w ,d g o 6/ A Z aw g a foz M M (a; $513 61mm 1 1 7 Nov. 25', 1930. H B, T Y OR 1,783,162

SYSTEM OF SPEED GOVERNING Original Filed May 16, 1919 4 Sheets-Sheet 2 awueM-toz NOV. '25, 1930. H; B, TAYLQR 1,783,162

SYSTEM OF SPEED GOVERNING Original Filed May 16, 1919 4 Sheets-Sheet 3 60 A; awvawfloz My /7 35% tilt-K7644011 4 J 7 Nav. 25, 193% H B. TAYLOR SYSTEM OF SPEED GOVERNING Original Filed May 16, 1919 4 Sheets-Sheet 4 Patent ed Nov. 25, 1930 HARVEY BIRGHARD TAYLOR, OF PHILADELPHIA, PENNSYLVANIA SYSTEM OF SPEED GOVERNING Original application filed May 16, 1919, Serial No. 297,552. 11ivide 1 and this application filed April 5,

1920. Serial No. 371,849. Renewed January 19, 1929. v

This invention relates to the governing of a rotary prime mover for power purposes such for instance as a hydraulic turbine. One object of the invention is to provide improved means for controlling the speed of a prime m'overj It is a further object to provide improved speed controlling means which will d1spense with the ordinary flyball governor as heretofore connected with each unit substituting therefor a simpler, electrical apparatus not requiring the complicated mechanical'connections hitherto necessary.

A further object of the invention is to adapted this electrical governor to a system of control from a separate source of predetermined speed so that a single central standard may be connected to control the speeds of a number of prime movers.

Other objects of the invention will appear in connection with the following description of the specific embodiments shown in the accompanying drawings in which:

Fig. 1 is a diagram showing an electromagnetic device for determining variations from the desired spec I Fig. 2 is a diagram showing how thedevice of Fig. 1 may be used to actuatethe turbine gates.

Figs. 3 and 4 are views of modifications.

Fig. 5 is a diagram of circuits adapteid tlo produce constant speed rotary motion Fig. 6 is a diagram illustrating thel 6135- rent variation in one of the circuits, and.

Figs. 7 to 15 are views of modified controlling means.

In an automatic governing system it is usual to have the speed variations of the in speed of the power electrically to the for instance by action between varies in correspondence with 1 theshaft or rotates a synchronous generator 61, the

alternating current circuits of which are connected to the ring of wlndmgs w of a sw1nging frame 122 in windings 'w" capable of rotating through The generator 61 rotates in prime mover and its circuits produce a rotating magnetic mall angles. ime with the fieldjor c1rcuit in synchronism with the generator 61 and consequently with the prime mover.

Within the pivoted frame or deflecting element 122 is a fixed element or stator 121 clamped in ring of windings 'w suitable supports and carrying a in the rotating magnetic field of the windings w. The relative rotation of the outer magnetic field induces a current in windings w which are closed on themselves through adjustable resistance 1', creating a reaction between the two rin of .swinging frame or deflecting element 122.

For a given setting of t t vary directly with the mover so that without nection between the s windings and exerting a torque on t e the resistance 1- this orque will vary with the rate'of rotation of he field in windings w and this in turn will speed of the prime any mechanical conparts there will constantly be a torque exerted on the frame 122 instantaneously equal to a function of the speed of the controlled unit transmitted to some device such as a fly-ball governor which corres ondingly regulates the supply of power to the unit. Such mechanical driving of the control device necessitates complicated and expensive mechanism in connection with each controlled prime mover, involving constant attention and repair and adjustment and often causing the controlled unit to be inoperable at critical times. In the control system of this invention this direct driving of a governor is avoided and the variations prime mover.

To use this torque to regulate the speed of he prime mover the system of this invention adapted to exert a predetermined count-er torque Just counter balancing the turning stance the springs 23 (see below collar 21 connected orque at the desired normal speed. For in- Fig. 2) above and to arm 19 may be adjusted to exert the desired counter pressure 0 balance a normal counter clockwise torque of frame 122*. Increase in the prime mover speed above the normal will increase the orque on the frame and will then lower arm 19 and compress the lower sprin an amount" For instance, as shown in Fig. 2 the arm 31 is connected to a valve rod or stem 32 carrying the two piston valve members 69 and 70 within the valve chamber 71. The conduit 81 admits pressure fluid from any convenient source to the valve chamber 71 between the valves 69 and 70, and the conduit 78 by its branches 79 and 80 serves to exhaust the fluid from either end of the valve casing 71.

The two ports 72 and 73 are connected by respective conduits 74 and 75 with the ends of the hydraulic cylinder 76 which contains the piston 77. The piston rod 82 and connecting rod 83 make connection with the arm 84 by which the ring 85 may be rotated around the main turbine axis 89. This ring 85 is connected to the turbine gates and as shown in the diagram, a counter-clockwise movement opens the gates. If desired another valve may be provided relay fashion,

. between the valve 69-70 and the cylinder 76 but for simplicity in the diagram, this is not shown.

In addition tc the arm 84, the gate control rin 85 also-carries an arm 86 connected by a link 87 with the valve restoring rod 26,

' which is pivotally connected with the floating lever 24. By means of the rod 27 another point of the floating lever 24 is connected to the piston within the dash pot 30. v

The arm 19 extending from the shaft 8 oppositely to the arm 31 is connected by links with the block 21 which slides up and down on the rod 22, between the springs 23. This rod 22 is connected to another point of the floating lever 24.

Within the casing 28 there is a usual spring tending to hold the rod at a certain normal position relative to the casing 28 or to restore it to that position when it is displaced.

" This rod 25 is also connected to the floating lever 24, the point of the connection being adjustable along the length of the lever 24 by means of the hand wheel 33. The normal position of the spring casing 28 may be adjusted by rotation of the gear wheel 29.

The normal steady state of the-apparatus with the turbine running without variation in speed is for the springs 23 tojust balance the frame torque at this normal speed and hold pistons 69 and over ports 72 and 7 3.

Supposethat an increase in load on the turbi'ne tends to slow it down, this will cause the decreased torque to permit lower spring 23 to expand raising arm 19 and connecting port 72 to the exhaust and port 73 to the source of pressure thereby opening wider the turbine gates. Similarly a lightening of the load on the turbine will result in a downward movement of arm 19 to restrict the opening through the turbine gates.

Whenever the pivoted frame 122" is rotated a small amount displacing the slide block 21, the end of the right hand extension 31 is given a corresponding motion which moves the pilot valve. This admits pressure, either by means of an intermediate relay or directly, to the main valve controlling the operating cylinder of the turbine, which is turn moves the turbine gates. The motion of the turbine gates is communicated to the restoring rod 26, (the middle rod connected to the smaller lever 24) and the first effect is to move the left hand rod 25 within the spring case 28 against the pressure of the'sp-ring, the lever 24 turning upon the right hand end as a fulcrum.

Whenever there is any quick change in speed of the main turbine unit there will be a corresponding quick motion of the extension 31 of the pivotal frame. This will raise or lower rod 32 connected to the pilot valve.

The opening of the pilot valve will cause through suitable relays a corresponding quick motion of the turbine gates. The gates in turn, through the restoring connection 26 will move the lever 24 at its point of connection with the link joining it to rod 26.

During this quick motion the right hand end of lever 24 where it is joined to the link from rod 27 will act asa fulcrum since rod 27 will not have time to move within the (lash pot 30. The result will be that the left hand end of lever 24 will be moved upward or downward carrying with it rod 25, and compressing or extending the springs within the spring case 28. The motion of the left hand end of lever-24 will raise or lower the rod 22,

the effect of which will be to restore the left hand end of extension 19 to its normal position and at the same time to restore the right hand end of extension 31 to normal position, closing the pilot valve.

Any change in speed of the main unit will, therefore, cause a limited movement of the turbine gates, but there will be no further motion of the gates unless'the speed of the main unit continues to change. So far the operation is complete, but is not entirely satisfactory for the reason that considerable changes of speed will be necessary to cause a change in the position of the turbine gates. The effect would be to permit too great a speed variation in the main unit between no load andfull load.

The nature of the medium acting Within the hydraulic turbine and its penstock will not permit an instantaneous regulation of speed'to an smaller degree of variation than the action ust described will provide. The inertia of the column of water occupying the turbine passages and penstock does not permit a very rapid opening or closing of the turbine gates since such a rapid gate motion would cause a severe rise or fall of pressure at the entrance to the turbine. This rise or fall of pressure tends to counteract the control imposed by the gate movement. For example, if the turbine gates are opened quickly the inertia of the water prevents its immediately issuing through the enlarged gate openings at the original velocity. The effect is to reduce the pressure producing the flow through the turbine, and if the gate motion is too rapid this reduction in pressure may more than offset the increase in the quantity flowing, so that instead of the governor causing an increased output of power from the turbine an actual reduction would be the result. It is seen that the action of the restoring connection 26 continually tends to oppose the motion of the turbine gates, and limits its motion so as to permit a considerable variation of speed of the main unit at times of quick changes of load on the generator, and it is clear that this variation of speed is necessary in any water power machine.

In spite of the above considerations there is nothing to prevent a gradual return of the speed to the normal value or to within any desired degree of variation from the normal value, it being merely necessary to make this adjustment sufiiciently slow to allow for the gradual acceleration or retardation of the water column filling the penstock and turbine passages. This is accomplished in this governor by means of dash pot 30 and the spring case 28. The springs within this case will slowly move the rod 25, causing the lever 24: to pivot about the pin connecting it with 26the rod 27 controlling the speed of this motion by means of dash pot 30. The result of this action is the moving of rod 22 toward its normal position.

In the system of this invention, therefore, a variable torque is used to control the power supply to the prime mover and this torque produced by the magnetic electrical fields and without mechanical connection between the parts. This torque will also be always instantaneously a function of the speed of the prime mover and its correctiv-e influence will be continuous, moving to maximum as the speeds separate and returning gradually to zero as the adjusting effect of the governing means is followed. It therefore tends to cooperate with the governing means to bring about a gradual approach toward the normal desired speed under all conditions of service and to 'hold the desired action between speed when reached without any excess in an opposite direstion or hunting back and forth between under speed and over speed.

In the modification illustrated in Fig. 3

the synchronous generator 61 is connected to of Figs. 1 and 2 and it is obvious that the same variable governing torque is developed between the relatively rotating electrical fields. v

The system of this invention is also adapted to develop this governing torque by comparison of the prime mover speed with the predetermined speed of a constant speed element. For instance a rotating electro-magnetic field synchronous with the generator 61, such as the field of windings ca in Fig. 1, may be brought into juxtaposition with another rotating field of predetermined constant speed so that the variation in the former will bring about a reaction with relation to the latter. In the modification illustrated in Fig. 4, the pivoted frame or deflecting member 122 has its windings w in synchronism with the speed of the prime mover, as in F ig; 1. Instead of the stator 121 however, a rotor 121 is used driven by shaft 2 at a predetermined constant speed corresponding to the normal speed of the outer field of windings 'w The rotor 121 carries short circuited windings or conductors in which no current is induced so long as there is no relative slip between the rotor and the rotating field. When, however, a variation in the prime mover speed causes relative rotation between the field and the rotor, current will flow in the rotor conductors setting up a magnetic field reacting on the outer field to produce a torque between them. This torque will vary with the variation of the prime mover speed and may be used to regulate the power to the prime mover as explained in connection with Fig. 1. In such a system the springs 23 holding arm 19 will be substantially balanced at normal speed as no substantial torque will then be present.

Such a system of speed comparison is particularly advantageous in permitting a number of power units to be controlled from a single standard of predetermined speed. For instance a central control device operated at constant speed for instance by means of a centrifugal governor, may be mechanically or electrically connected to drive at constant predetermined speed the shafts 2' of rotors 121 of governors (Fig. 4) associated with each separate power unit, the corresponding windings 'w of each governor being in synchronism with its particular unit. A single producing a'rotating field central constant speed control thus will replace the usual centrifugal governors at each unit.

Such a standard central control of electrically operated type is shown in the system of this invention, in Fig. 5, wherein a source 101 of D. C. current operates a'D. 0. motor 102,

. the motor 102, and the arrangement therefore provides a method of adjusting the speed. The rheostat 105 controlling the shunt circuit may be adjusted so that just enough variation of field current is provided to take care of the fluctuation in load and voltage. The motor is direct-connected to a single-phase generator 109 and a three-phase synchronous generator 110, the shafts of all three machines being coupled together. The three-phase generator 110 supplies constant frequency current which is utilized as the standard for controlling the speed of all the units in the power system. In order to maintain this frequency at a constant value, the

speed of this motor generator set is regulated by means of a resonant circuit supplled by the single-phase generator 109. This circuit contains a capacity 111, an inductance 112 and a resistance 113 having such values that the circuit has a natural resonant frequency agreeing with the frequency which is p to be malntained'in-the standard frequency the resonant circuit will be so adjusted that circuit. For example, if the standard fre-.

quency is to be cycles, the constants of if this circuit is subjected to an alternating potential having a gradually increasing frequency, very little current will tend to flow in the circuit. until the period of resonance is approached. When the frequency reaches, say, 99 cycles, a rapidly rising current will begin to flow which Will reach its maximum at say 101 cycles, and for higher frequencies will then fall off once more. This is shown diagrammatically in Figure '6. As the freclose contacts 107 by action of the solenoid shown. The contact-making ammeter device 106 will thus serve to provide a limitation for 102 and single phase generator 109 has/itsv circuits W drivin synchronousmotor 110 connected by sha t 2 to a rotor 121 of a torque device T the movable stator or defiect-.

ing element 122 of which has its winding supplied from alternating current generator 61 driven by shaft 60 of the prime mover which is to have its speed controlled. .The rotatin field of the stator 122 will normally be substantially in step with the rotor 121 so that no torque will e transmitted from one member to the other, the windings of rotor 121 being short circuited upon themselves and so long as the speed of rotation of this field of stator 122 is the same as the speed of rotation of rotor 121 there will be no current induced in these windings and no torque or turning movement exerted by rotor 121 on stator 122. When however the rotational speed of the field of stator 122 varies from that of rotor 121 a current will be induced in the rotor windings and a resultant torque will be exerted upon stator 122 tending to turn it in one direction or the other depending upon whether the stator field speed exceeds or lags behind the rotor.

The wires W conveying constant frequency current from the central generator 110 permit easy connection to distant points so that all the power units may be controlled from this single central constant speed unit. These wires W may also be directly connected to the electrical circuits of the governing torque device. For instance in Fig. 7 these wires pass directly from the synchronous generator 110 to the windings 'w of the deflecting element 122', the rotor 121' of which is driven by shaft 2 from the prime-mover 60 The windings w of the rotor are closed on themselves and as soon as there is any variation in speed between the rotating field of windings w and the rotor the current set up in the rotor windings w will develop a reacting field exercising a governing torque on the pivoted frame or deflecting element 122'.

The system of Fig. 8 is similar to that of Ill Fig. .7 but the rotating element is supplied with constant frequency current through slip rings 141 so connected that the resulting magnetic field rotates relatively to the rotating element in the opposite direction to the mechanical rotation of the latter. Hence if the two speeds are the same the magnetic field (rotating element) remains stationary in space and there is no tendency for the stator 122 to be deflected. The deflectingelement 122' carries windings closed upon themselves through an adjustable resistance.

The Fig. 9 combination is similar to that of Fig. 8 but with the further modification that the rotating element 121' of the torque device is driven. by synchronous motor 140,

and supplied through slip rings by the va riable frequency current from the generator 61 of the prime mover 60, the windings of the stator or deflecting frame being closed upon themselvesas in Fig. 8. The motor 140 would be supplied with constant frequency current by generator 110, as in Fig. 1.

In the modification of Fig. 10 the stator frame 122 has its windings supplied by gen erator 61 to produce a rotating field, the rotor part 121 does not itself rotate but is supplied with constant frequency alternatmg current as by synchronous generator 110 to produce a rotating field within the field of stator 122 and revolving normally at the same speed. When these two speeds coincide there will be no tendency for the frame 122 to move and it will remain in normal position. If, however, owing to a change of speed of the main unit, a difference in speed should occur, frame 122' will tend to rotate in much the same manner as the rotor of an induction motor. This motion will be resisted by the springs 23 and there will result a deflection of the slide block 21.

The system of Fig. 11 is similar to that of Fig. 10 but with the connections of the torque device reversed, the frame being supplied from generator 110 and the fixed part from generator 61.

Inthe modification shown in Fig. 12 two series of windings in the deflecting frame 122 are supplied respectively with constant frequency current and the current synchronous with the speed of the prime mover in such way as to create two rotating fields turning in opposite directions. The other element of the torque device is fixed and its windings are closed upon themselves and may, of course, be provided with adjustable resistance in circuit.

In the combination of Fig. 13 one element 121 of the torque device is fixed and the windings of the deflecting frame 122 are supplied by a circuit which is continuous from the constant frequency source of cur- .rent through the windings and to the synchronous generator 61 direct-connected to the prime mover 60. This circuit will correspond to that connecting two similar synchronous machines. When these machines are running in exact phase and at equal voltages no current will flow. In the event of any unbalance of phase or voltage the current will flow and will set up torque in the deflecting frame.

In Fig. 14 the connections are similar to cascade connections of two induction motors.

The synchronous generator 110 supplies cur rent through slip rings 145 to induction generator 146 driven by main shaft 60. The conductors of the stator frame 147 of this generator are connected to the windings of deflector frame 122, the fixed element 121 having its windings closed on themselves. The rotor field of the induction generator 146 revolves relatively to the rotor in a direction opposite to the rotation of the rotor but upon a difference in speed between the rotor and its field a differential frequency current will be set up in the conductors of frame 147 which will cause a torque between the deflector elements 121 and 122".

The system of Fig. 15 is similar to that of Fig. 14 except that the constant frequency current is connected to the conductors of stator 147 in such manner as to produce a field rotating in the same direction as the induction generator 146. A sli between this rotating field and generator W1 1 cause a differential frequency current to flow through slip rings 145 to the windings of deflector frame 122 setting up a governing torque in said frame. In the species of Figs. 14 and 15 the torque device may be any suitable form of A. C. motor with one element held stationary and the other arranged to oscillate or rotate against springs. The frequency of the circuit supplying the torque balance for any given speed difierential canbe varied by varying the relative number of poles of the stator and rotor windings of the induction generator 146.

In the system of this invention using a central control for a number of separate power units the duplication of complete governing aparatus at each unit is avoided and thus attaining great simplification and saving in cost. For aside from the disadvantages due to its mechanical complication, the effects of friction, fati ue of springs, wear of joints etc., directly a ect the speed of the turbine; and any variation in weight of the fly balls, etc., or of the spring characteristics also af fects the speed. Moreover, the necessity for rotating the governor at a high speed by a mechanical drive from the mam shaft of the turbine, the difliculty of maintaining lubrication in the rotating mechanism, the necessity for shutting down the rotating system for examination of parts of the governor, the effect of small changes in friction of the governor on the normal speed of the turbine, all these are difficulties thatattend the use of centrifugal governors in this connection and are overcome by the system of this invention.

It should also be noted that in this system the separate units as to their performance are individually adjustable without impairing the system asa whole and without affecting the remaining units. For instance with the gate moving means of Fig. 2, the point of 33 with respect tothe pin connecting 22 with 24. If these two points are brought together the speed of the main unit may be brought back to normal for all positions of the turbine gates. If a slight difference in position is permitted any desired drop speed between no load and full load may-be provided. This no load to full load drop may beused for instance to secure the proper automatic sharing of load between a number of alternators running in parallel. The amount of this allowance is adjustable by means of hand wheel 33. The position of the spring case 28 is adjustable as already mentioned. The effect of adjusting this spring case is to impose on the unit a tendency toward a constantdifl'erence in speed between the unit and the standard.

When the unit comprises an alternator running in parallel with other similar units, it will continue to run in step with the other units, and the adjustment of the spring case will merely have the effect of causing the unit to assume a larger or smaller share of the station load. Y

While the system of this invention has been described in connection with specific embodiments, its principle is not confined thereto, but is intended to cover such modifications thereof as fall within the scope of the appended claims. I

Figs. 4 and 10 of this application are a division of my copending application, Serial No. 297,552, for System of speed governing, filed May 16, 1919.

1. In apparatus for governing the speed of a prime mover, two sets of windings, one of which is supplied with current from a gen erator having a speed proportional to that of-said prime mover, said windings being capable of acting upon each other electro magnetically to produce relative torque, and one of said sets being mounted on a fixed member and the other on a member capable of deflection in either direction from a normal intermediate position, irrespective of the load provided the prime mover is operating at normal speed, spring means to control the amount of said deflection, and means for utilizing said deflection to regulate the speed of.the prime mover.

2. In a system of speed governing, the combination with means for producing current of substantially constant frequency, of means for producing alternating current in synchronism with the part to be governed, and means for causing an interaction of said currents and developing a resultant control therefrom comprising an oscillatory deflectable member having windings for one of said currents thereon.

3. In a system of speed governing, the combination with means for roducing current of substantially constant requency, of means for producing alternating current in synchronism with the part to be governed, and means for causing an interaction of said currents and developing a resultant control therefrom comprising an oscillatory deflectable member having windings for one of said currents thereon, and an associated member producing a rotary magnetic field by means of the other of said currents.

4. In a governing system for a hydraulic turbine the combination with gate mechanism adapted to control the speed of the turbine of electrical means developing a force proportional to the difference in speed between an independent constant speed standard and the speed of said turbine, and defiectable means moved in either direction from a normal intermediate position, irrespective of the load provided the prime mover is operating at normal speed, by said force an amount proportional to said speed diflerence and adapted to actuate the turbine gate mechanism to control the speed of the turbine.

5. In a governing system for a hydraulic turbine the combination with electrical means having two independently produced fields 6. In a system of speed governing for a .1

hydraulic turbine, the combination with flow control means and fluid pressure operating means comprising a governing member controlling the position of said'means movable in either direction from a normal intermediate position, of electrical means including two interacting -independently produced fields adapted to efi'ect a variable force for operating said member and for varying said force according to the speed of the turbine and independently of the position of said control means.

7. In a turbine regulating system, gate operatmg mechanism and a controlling means therefor comprising a device responsive to the diflerence between the speed of the turbine and a standard speed, said device consisting of two inductively related elements, each adapted to produce a rotary magnetic field, the speed of rotation of one field being proportional to the speed of theturbine and the speed of the other field being that of the standard, the said elements being so constructed and arranged that one of said elements is moved by a force proportional to standard and th 0 directly from said the difference in'said speeds, and connections mechanism.

8. In a turbine regulating system, gate operating mechanism and a controlling means therefor comprising a device responsive to the difference between the speed of the turbine and a standard speed, said device consisting of two inductively related elements, each adapted to produce a rotary magnetic field, the speed of rotation of one field being proportional to the speed of the turbine and the speed of the other field being that of the standard, the said elements being so constructed and arranged that one of said elements is moved by a force proportional to the difference in said speeds, and connections between said element and gate operating mechanism comprising gate restoring mechamsm.

9. A turbine regulating system of the type wherein the turbine gates are controlled from a speed responsive device whose operation is limited from the turbine gates by a restoring mechanism, characterized by the fact that the speed responsive device comprises tWo inductively related windings, means for supplying current to one of said windings having a characteristic which varies with the speed of the turbine, means for supplying to the other of said windings current having a fixed characteristic corresponding to a speed standard, and means for producing an operating force through the interaction of the currents in said windings.

10. The method of governing the speed of a prime mover consisting in independently producing two interacting rotating fields in 'synchronism respectively with a frequency e prime mover, and controlling the power supply to the prime mover in gciqrdance with the differential speed of said 11. The method of governing the speed of a prime mover which consists in operating two independently produced rotating fields of a differentiaLspeed apparatus, one of said 'fields being in synchronism with .said prime mover, the other in synchronism with a frequency standard, and controlling the power supply to the prime mover in accordance with the differential speed of said fields by mechanically transmitting an operating force apparatus.

12. The combination in a governing system for a prime mover having an adjustable element to control its speed and frequency, comprising a differential speed apparatus having 'two associated means for producing magnetic flux forming rotating fields respectively in synchronism with said prime mover and a frequency standard, and means for mechanially transmitting an operating force from said apparatus to actuate said element in accordance with the differential speed of said between said element and gate operating' 13. A governing system for a prime mover driving an alternating current generator, comprising valve mechanism for controlling the supply of actuating medium for said prime mover, and means, includin magnetic and electrical circuits energized %y current received from said generator, adapted to be in a balanced state so long as said generator operates at a predetermined value of frequency'and being rendered in an unbalanced state when there is a difference of frequency in the current of said generator and said predetermined value of frequency, said electriccal circuits being operative upon said magnetic circuit and all of said circuits comprising a unitary arrangement, and means adapted to effect actuation of said valve mechanism when said unbalanced state is brought about.

14. A governing system for a prime mover driving an alternating current generator, comprising valve mechanism for controlling the supply of actuating medium for sa d prime mover, and means, including magnetic and electrical circuits energized by current received from said generator, adapted to be in a balanced state so long as said generator operates at a predetermined value of frequency and being rendered in an unbalanced state when there is a difierence of frequency in the current of said generator and said predetermined value of frequency, a member adapted to be deflected by the magnetic portion of said circuit when said state of unbalance, and means controlled by said deflectable member to effect actuation'of said value mechanism when said unbalanced state is brought about.

15. The combination set forth in claim 14: further characterized by having the magnetic portion of said circuit, during said unbalanced state, deflect said member from a neutral point at which said member, irrespective of the generator load is normally positioned so long as the generator operates at the predetermined value of frequency.

16. The combination set forth in claim 14 further characterized by having the magnetic portion of said circuit, during said unbalanced state, deflect said member from a neutral point at which said member, irrespective of the generator load is normally positioned so long as the generator operates at the predetermined value of frequency, said member being deflectablc in either direction from said neutral point in accordance with an increase or decrease in generator frequency from said standard value.

17. The combination set forth in claim 14 further characterized by having the magnetic portion of said circuit, during said unbalanced state, deflect said member from a neutral point at whlch said member, irrespective of the generator load is normally positioned so long as the generator operates at the predetermined value of frequency, and restoring mechanism, for said valve mechanism, operative upon movement of said valve mechanism even during continued variation of the generator frequency from the standard value of frequency.

18. A governing system for a hydraulic turbine driving an alternating current generator, comprising servo motor operated gate mechanism for controlling fluid flow to the turbine, a servo-motor for actuating said gate mechanism, a distributing valve, a pilot valve for the distributing valve, electrical circuits at least a part of which receive current from the generator, means providing a magnetic circuit upon which said electriccircuits directly act, a member deflectable by said magnetic means in one or the other of opposite directions from a neutral point at which point said member, irrespective of the generator load, is normally positioned so long as the generator operates at a predetermined value of frequency, means controlled by said deflectable member for eifecting actuation of said pilot valve when deflection of said member occurs, restoring mechanism operable upon said distributing valve during servo-motor movements, and a secondary restoring mechanism 30 operable upon said pilot valve.

HARVEY BIRCHARD TAYLOR.

cruuricara or con crioN.

, Patent No. 1,783,162.

- HARVEY amcuaao rartoa it is hereby certified that error appears in the printed-specification oi the above numbered patent vrequiring correction as "follows: :Page 7, II-fine t claim 14 ior "circuit when" read circuits during and line 103 f I t or value" read-valve and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of 'the case in the Patent Off g ed and sealedthis 24th dayof March, A, 1931. f

M. J. Moore,

' Acting Commissioner of. Patents.

.GrsntedNovember 25, i930, to 

